1. Field of the Invention
Embodiments of the present invention relates to a bioreactor apparatus adapted to reduce a nitrogen content in an aqueous stream to a desired low level. The present invention also relates to a novel method and apparatus for near complete adsorption and conversion of nitrates from liquids adapted to the removal of nutrients from liquids by absorption.
More particularly, embodiments of the present invention relates to a bioreactor apparatus adapted to reduce a nitrogen content in an aqueous stream to a desired low level, where the apparatus includes a solid nitrogen absorbent, a aqueous bioactive solution, an inlet, an outlet, an aerobic section, an anaerobic section and an absorbent and solution circulation assembly. In certain embodiments, the apparatus of this invention can reduce a nitrogen content of the aqueous stream below about 10 ppm total nitrogen. In certain embodiments, the apparatus of this invention can reduce a nitrogen content of the aqueous stream below about 5 ppm total nitrogen. In certain embodiments, the apparatus of this invention can reduce a nitrogen content of the aqueous stream below about 1 ppm total nitrogen. In certain embodiments, the apparatus of this invention can reduce a nitrogen content of the aqueous stream below about 0.1 ppm total nitrogen.
2. Description of the Related Art
Bio-remediation has become an increasingly versatile part of remediation of waste materials. Bio-remediation can use used to help clean up oil spills, remove sulfur from compounds, remove nitrogen from compounds and other uses.
Current methods and apparatus used to effect the removal of nitrates are regenerative absorption columns, non-regenerative absorption columns, bioreactors, reverse osmosis, biofilters and traditional suspended denitrifying biological processes. For example, reverse osmosis systems are expensive, are subject to both biological and chemical fouling, use more energy than all other methods, and generate a high strength, usually toxic waste stream requiring expensive secondary treatment and or disposal.
Absorption columns use expensive media, require media replacement or regeneration, produce waste streams more toxic than the water to be treated, require periodic cleaning due to biological fouling and/or plugging by suspended solids, produce a second waste stream, include complicated piping and valves, are adversely affected by ions that compete with nitrogen and numerous compounds that poison the media.
Bioreactors and biofilters have narrow performance bands, are subject to biological fouling requiring parallel units or additional surge equipment for periodic cleaning, are limited to low nitrate concentrations that don't inhibit biological activity, cannot tolerate rapid concentration changes, require multiple days from startup until water can be treated, and are difficult to predict the length of time after startup to reach full performance.
Denitrifying biological processes require large areas, are effected by cold weather, are limited to low nitrate concentrations that do not inhibit biological activity, require large volumes to tolerate rapid concentration changes, require multiple days from startup until water can be treated, and are difficult to predict the length of time after startup to reach full performance.
Biological regeneration of absorption media has been commercially employed under patent (trade name is PACT), using activated carbon and continuous stirred tank reactors. The method and various apparatus employed are suspended biological processes using the activated carbon to absorb organic compounds and are not suited to nitrate removal. The method or apparatus used cannot completely regenerate the carbon without removal and use of external processing. It is typical of the commercial systems deployed to completely encase the activated carbon with biological growth rendering it inert and requiring constant replacement.
Although denitrification/bio-remediation apparatuses and methods have been introduced in the past, there is still a need in the art for a bio-denitrification apparatus capable of reducing a nitrogen content of an aqueous stream below a desired low level, where the low level is less than 10 ppm total nitrogen. In many embodiments of the present technology, the nitrogen level is less than or equal to about 3 ppm.